Liquid crystal display apparatus
An IPS-mode liquid-crystal display apparatus for controlling transmission and cutoff of light by applying a cross-directional electric field to liquid-crystal molecules horizontally oriented reduces diagonal luminance rise and coloring at the time of black display by a simple configuration. A configuration is used in which an optical phase compensation member for canceling the double refraction property of a polarization-plate support base material is provided between the liquid-crystal-layer-side support base material of a lower polarizer and a liquid-crystal layer. Or, a configuration is used in which the optical phase compensation for canceling double refraction property of the polarization-plate support base material is provided between the liquid-crystal-layer-side support base material and the liquid-crystal layer.
The present invention relates to a liquid crystal display apparatus displaying black representation, particularly to an in-plane-switching-mode (IPS) liquid crystal display apparatus in which liquid crystal molecules are homogeneously oriented to control transmittance of light by applying a horizontal electric field to the liquid crystal molecules and a great improvement of its viewing angle characteristics (particularly, displaying black representation and low gray levels).
As a method for applying the direction of an electric field to liquid crystal in the direction parallel with a substrate (hereafter referred to as horizontal electric field method or IPS mode), a method using a comb-teeth electrode provided on one substrate is disclosed in JP-B-63-21907, JP-A-9-80424, and JP-A-2001-056476. Because a liquid-crystal molecule rotates mainly in a plane parallel with a substrate, it is known that the difference between birefringence at the time of electric field application and at the time of no electric field application viewed from a diagonal direction is small and the viewing angle is wide.
However, in the IPS mode, it is known that light leaks depending on the characteristic of the polarizer when viewing from a diagonal direction, which is in an orientation deviated from the absorption axis of a polarizer, while a change of the double refraction factor of liquid crystal is small. To eliminate the diagonal light leak of the polarizer, a method for using a retardation film is disclosed in JP-A-2001-350022. However, though this document basically considers the improvement of viewing angle of only a polarizer and influence of liquid crystal for a VA mode, a method for compensating the influence by a liquid crystal layer is not disclosed for the IPS mode.
Moreover, means for solving a problem of a color change of white depending on an observation direction is disclosed in Japanese Patent No. 3204182. However, improvement of black representation characteristic is not described.
Furthermore, Japanese Patent No. 2982869 discloses a configuration for placing a wave plate on one inner side of a polarizer in order to improve the viewing angle characteristic of black display. However, it has been found by our study that though this method considers the influence of a support base material TAC (tri-acetylcellulose) provided on both sides of the polarizer, black does not completely dark at a diagonal viewing angle with phase compensation by one sheet at either side and that the method does not provide a configuration which decreases coloring due to wavelength dispersion in the liquid crystal layer. Moreover, it does not disclose phase compensation differences depending on whether the orientation axis (lag axis) of a liquid crystal molecule at the time of black representation is parallel with or vertical to the polarizer at the incoming side, which is our invention. In the case of the above-described well-known example, the visual-angle characteristic is discussed only by brightness characteristic but the corresponding method to this color change is not disclosed.
SUMMARY OF THE INVENTIONA problem to be solved is that increase of brightness and coloring could occur in a diagonal direction in an in-plane-switching-mode (IPS) liquid crystal display apparatus in which a liquid crystal molecule has homogeneous orientation at the time of black display and which controls transmission and cutoff of light by applying a horizontal electric field to the liquid crystal molecule.
The IPS mode uses two polarizers arranged so that a liquid crystal molecule having homogeneous orientation in horizontal direction and an absorption axis are orthogonal in vertical and horizontal directions for the screen front. Therefore, when viewing the screen from vertical and horizontal directions, absorption axes of two polarizers are orthogonal and homogeneous-orientation liquid crystal molecule and one-hand polarization-plate absorption axis are parallel. Therefore, it is possible to sufficiently decrease black luminance. However, because the angle formed between absorption axes of two polarizers is deviated from 90°, thereby transmitted light causes double refraction, and light leaks when diagonally viewing the screen from the direction of an azimuth angle of 45°, so that it is impossible to sufficiently decrease black luminance. Moreover, an amount of diagonal leaked light depends on a wavelength, and coloring occurs. Therefore, it is an object of the present invention to provide means for decreasing luminance rise and coloring of black display when viewing black display from a diagonal direction in order to obtain preferable display at every angle of the whole azimuth on black display in the IPS mode. Furthermore, the IPS mode has a problem that when viewing the IPS mode from the front, particularly at the time of black display, in-screen display irregularity and contrast ration decrease tend to occur. The present invention also provides means for improving these problems by using the optical phase compensation technique.
The present invention is a liquid crystal display apparatus including a liquid crystal layer in which absorption axes of a first substrate having a light-incoming-side polarizer and a second substrate having a second polarizer are almost vertical (smaller angle ranges between 88 and 90°) and a liquid crystal molecule is oriented so as to be parallel with the substrates and almost vertical to or almost parallel (smaller angle ranges between 0 and 2°) with the absorption axis of the first polarizer and rotates on a plane parallel with the first substrate by applying an electric field in the direction parallel with the first substrate and a matrix-driven electrode group having a pair of electrodes by facing each pixel is provided and a back illumination apparatus is included, the first and second polarizers are polarizers respectively having a support base material at both sides of a polarization layer and the support base material has a double refraction property (retardations in plane and in thickness direction are 10 nm or more), an optical member or film having double refraction property is provided to the liquid crystal layer side of the first or second substrate, a refraction factor is almost isotropic (retardations in the plane and the thickness direction are 10 nm or less) when laminating the polarization-plate support base material contacting with the substrate on which the optical member or film is provided and the optical member or film or absorption axes of a first substrate having a first polarizer at the light incoming side and a second substrate having a second polarizer are almost vertical (smaller angle ranges between 88 and 90°), a liquid crystal molecule is oriented in parallel with the substrates and almost vertical to or almost parallel (smaller angle ranges between 0 and 2°) with the absorption axis of the first polarizer, and the liquid crystal molecule rotates in a plane parallel with the first substrate by applying an electric field in the direction parallel with the first substrate, a matrix-driven electrode group having a pair of electrodes by facing each pixel is provided to the side of either of the first substrate or the second substrate whichever is closer to the liquid crystal layer. The first and second polarizers are respectively a polarizer having a support base material at both sides of a polarization layer, the support base material has double refraction property (retardations in plane and thickness direction are 10 nm or more), a support base material provided to the liquid-crystal layer sides of the first and second polarizers respectively show almost-equal double refraction property (retardation differences in the plane and thickness direction are 20 nm or less) and an optical phase compensation member having double refraction property (retardation difference in the plane or thickness direction is 20 nm or more) is provided between the liquid crystal layer and the second substrate.
Other means will be described in embodiments in detail.
A liquid crystal display apparatus of the present invention can decrease the influence of a liquid crystal layer in a diagonal visual field by a configuration using a polarizer, liquid crystal layer, and optical phase compensation member and specifying the phase difference of each optical phase compensation member.
Other objects, features and advantages of the invention will become apparent from the following description of the embodiments of the invention taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Contents of the present invention are specifically described below.
While a liquid-crystal TV becomes conspicuous, the following is important for a liquid crystal display which is not light-emitting: how to transmit the light from an illumination apparatus at the time of white display and how to cut off the light at the time of black display. The present invention particularly relates to how to eliminate coloring in addition to reduction of luminance when viewing black display from a diagonal direction.
First, definition is described by referring to
Then, in the case of a pair of polarizers orthogonal to each other, the reason of light leak is considered by assuming the viewing angle θ and azimuth angle Φ as θ≅0°, Φ=0°, and 180°±90°. As shown in
To understand these polarized states, it is very preferable to use Poincare sphere display. The Poincare sphere display is disclosed in Japan Society of Applied Physics Optics Gathering for Friendly Discussion “Crystal Optics” printed by MORIKITA SHUPPAN Co., Ltd., First Edition Fourth Issue in 1984, Chapter 5, pp. 102-163. When taking x and y axes on a face vertical to the traveling direction of light, assuming the electric field amplitudes as Ex and Ey and the relative phase difference between Ex and Ey as δ(=δy-δx), Stokes parameters S0, S1, S2, and S3 are shown by the following expressions.
S0=<|Ex|2>+<|Ey|2>
S1=<|Ex|2>−<|Ey|2>
S2=<2ExEy cos δ>
S3=<2ExEy sinδ> (Expression 1)
In the case of complete polarization, S02 is equal to S12+S22+S32. Moreover, when displaying it on the Poincare sphere,
S1=cos La cos Lo,
S2=cos La sin Lo,
S3=cos La. (Expression 2)
In this case, on the Poincare sphere, clockwise polarized light is provided on the upper semisphere, counterclockwise polarized light is provided on the lower semisphere, linear polarized light is provided on the equator, and right-handed circularly polarized light and left-handed circularly polarized light are provided on upper and lower poles.
When considering the states in
In
R·h=((nx+ny)/2−nz)·h (Expression 3)
A polarized state is not influenced in the case of vertical incoming but a polarized state is changed by being influenced by a support base material at the time of diagonal incoming by the retardation R·h. In this case, a change of polarized states is considered in accordance with the optical layer configuration shown in
Moreover, light of 550 nm is considered for
From the above mentioned, it is known that light leak and coloring at a diagonal viewing angle at the time of black display of the IPS-mode liquid-crystal display apparatus are greatly different from the case of orthogonal-layout polarizer.
Moreover, according to this idea, it is found that a polarized-state change by a liquid crystal layer most contributes to coloring. That is, it is a problem to decrease light leak in a diagonal direction while decreasing the influence of a liquid crystal layer at a diagonal viewing angle at the time of black display by an optical phase compensation member. The present invention solves the problem.
The present invention is described below.
Though
nx>ny≈nz (Expression 4)
Δn·dr=(nx−ny)·dr
A medium which has a refraction anisotropy only in the face and whose thickness-directional refraction factor is almost equal to that of a medium having a small in-plane refraction index is referred to as a positive a-plate and hereafter, the retardation of the positive a-plate is referred to as in-plane retardation. A polarized-state change when straight-line polarized light enters the positive a-plate is shown by rotation conversion using the optical axis having a large refraction factor (y direction in this case), that is, using the lag axis as an axis on the Poincare sphere. In the case of the optical configuration in
Then, polarized state changes before and after passing through the optical phase compensation member 13 and second polarizer support base material 11B are considered. As shown in
That is, in the case of o-mode, by canceling the double refraction of the first polarizer support base material 12B by the optical phase compensation member 17 set between the first polarizer support base material 12B and the liquid-crystal layer 15 and setting the optical phase compensation member 13 between the liquid-crystal layer 15 and the polarization layer 11C of the second polarizer, it is possible to eliminate the influence of the liquid-crystal layer on diagonally incoming light and reduce light leak. Because there is no influence of the liquid-crystal layer, it is possible to reduce coloring and light leak for diagonally incoming light.
Then, the case of e-mode shown in the right of
That is, in the case of e-mode, as shown in
Moreover, as shown in
In
The concept described up to now by using
In
The detailed example of the concept described above is shown in the following embodiments.
EmbodimentsBy showing specific examples below, the content of the present invention is more minutely described. The following embodiments show specific 20 examples of the content of the present invention but the present invention is not restricted to these embodiments. In the case of the embodiments, a result of numerical calculation and study using an optical simulation using the 44 matrix method disclosed in the thesis title of J. Opt. Soc. Am. “Optics in Stratified and Anisotropic Media: 4×4-Martrix Formulation” written by D. W. Berreman 1972, volume 62, No. 4, pp502-510 is included. In the case of the simulation, the spectral characteristic between three band cold cathode fluorescent lamp, spectral transmission characteristics of R, G, and B color filters are used and the spectral characteristic of 1224DU made by NITTO DENKO CORP. is used as a polarization-plate polarization layer. Moreover, nematic liquid-crystal having normal light refraction factor of 1.573 and abnormal light refraction factor of 1.484 is assumed as a liquid-crystal molecule included in a liquid-crystal layer and the thickness of the liquid-crystal layer is provided to 3.9 μm. Moreover, though wavelength dispersion of an optical phase compensation member uses one of polycarbonate (PC), polystyrene, norbornane, and liquid-crystal macromolecule, it is not restricted to but it is not restricted to them. Furthermore, in the case of the present invention, it is assumed to set an optical phase compensation member between a first substrate and a second substrate. However, this technique is disclosed in JP-A-2005-3733. According to our study, one of problems of the technique lies in the flatness of surface. When setting the optical phase compensation member between the first substrate and the second substrate and there is irregularity on the surface of the optical phase compensation member, the irregularity becomes fluctuation of the thickness of a liquid-crystal layer to cause in-plane display irregularity or contrast deterioration. However, according to our study, in the IPS mode using the fringe field electric field proposed in JP-A-2001-056476, in-plane display irregularity or contrast deterioration hardly occurs for thickness fluctuation of the liquid-crystal layer. Therefore, it is possible to easily combine the IPS mode with the technique for setting the optical phase compensation member between the first substrate and the second substrate.
Moreover, the expression such as vertical or 90° used in embodiments does not represent completely vertical. Therefore, even if rereading the expression as almost vertical or the smaller angle ranges between 88 and 90°, it does not influence the essence of the story. The same is applied to the expression such as parallel.
It is possible to directly use conventional liquid-crystal cell, electrode structure, substrate, polarization layer of polarizer objects having been used so far as IPS. The present invention relates to the specification and configuration of an optical member.
Moreover, a smaller angle (pretilt angle) for the substrate of a liquid-crystal-layer optical axis for a liquid-crystal layer while voltage is applied is provided to 0° in the simulation shown in embodiments. However, a large difference does not occur in the trend shown by this embodiment in a range of ±3°. However, the case of the pretilt angle of 0° shows the most preferable characteristic.
Embodiment 1
Nz=(nx−nz)/(nx−ny) (Expression 5)
In this case, the optical axis direction having a large in-plane refraction factor is referred to as the lag axis of a optically biaxial optical phase compensation film. In
Moreover, it is assumed that the liquid-crystal-layer-side support base materials 12B and 11B of the first and second polarizers are formed of triacetylcellulose and in-plane retardation is provided to 1 nm and the thickness-directional retardation is provided to 50 nm. According to our study, the double refraction factor can be canceled by a positive c-plate having thickness-directional retardation of 50 nm. Therefore, the positive c-plate having the same characteristic is selected as the optical phase compensation member 17 set between the first substrate 16 and the liquid-crystal layer 15.
In this case, an object whose refraction factor is isotropic in a face and has a large thickness-directional refraction factor is referred to as a positive c-plate. When showing the retardation R·h by an expression in accordance with Expression 3, the following expression is obtained.
nz>nx≅ny (Expression 6)
R·h=(nz−(nx+ny)/2)·h
Hereafter, the retardation of the positive c-plate points the thickness-directional retardation.
According to this configuration, the polarized state conversions shown in
In this case, the viewing angle characteristic at the time of black display is greatly changed by the retardation of the optically biaxial optical phase compensation film 13. Therefore, it is necessary to decide the retardation in accordance with optical simulation. Because an object of the present invention is reduction of luminance change and color change, each evaluation index is introduced.
As the index of luminance change, the maximum transmittance for changing viewing angles is introduced. In this case, the transmittance is obtained by considering visibility at an incoming wavelength of 400 to 700 nm. This is described by referring to
Then, Δxy is introduced as the index of color change.
First, on a case in which the optical phase compensation member 17 is not set and the double refraction factor of the support base material 12B of the first polarizer is not canceled in
As described above, by using the configuration in the case of o-mode shown at the left of
Moreover, the liquid-crystal-layer-side support base material 12B of the first polarizer is formed of triacetylcellulose and it is assumed that the in-plane retardation is 1 nm and the thickness-directional retardation is 50 nm. Therefore, the positive c-plate having retardation of 50 nm is selected as the optical phase compensation member 17 between the first substrate 16 and the liquid-crystal layer 15 similarly to the case of the embodiment 1. Moreover, in the case of this embodiment, it is assumed that the liquid-crystal-layer-side support base material 11B of the second polarizer is so small that it can be ignored. According to this configuration, the polarized state conversions shown in
This embodiment uses the configuration at the left of
Moreover, in
The structure of this embodiment is shown in
According to this configuration, the polarized state conversions shown in
As an example,
In the case of this embodiment, as shown in
Moreover, in the case of this embodiment, the polarized state conversions in
The structure of this embodiment is shown in
According to this configuration, the polarized state conversions shown in
In the case of this embodiment, as shown in
Moreover, in the case of this embodiment, the polarized state conversions in
The structure of this embodiment is shown at the left of
In this case, a plate which has refraction factor anisotropy in the face and whose thickness-directional refraction factor is almost equal to that of a plate having a large in-plane refraction factor is referred to as negative a-plate. When showing retardation by an expression in accordance with Expression 4, the following expressions are obtained. Hereafter, it is assumed that the retardation of negative a-plate points the following in-plane retardation.
ny≅nz>nx (Expression 7)
Δn·dr=(ny−nx)·dr
The negative a-plate includes two main axes respectively having a large refraction factor. When hereafter describing the lag axis of the negative a-plate, it is assumed that lag axis points a direction in which an in-plane refraction factor is large (direction of ny in Expression 7).
According to this configuration, the polarized state conversions shown in
When assuming that retardations of the polarization-plate support base materials 12B and 11B as 260 nm and the retardation of the optical phase compensation member 17 as 170 nm, the maximum transmittance becomes 0.0821% and Δxy becomes 0.133. It can be understood that a preferable viewing angle characteristic is obtained from the above configuration.
As shown in
This embodiment uses the configuration shown in
The structure of this embodiment is shown at the left of
The polarized state conversions shown in
As being understood by comparing
As shown in
Though this embodiment uses the configuration shown in
The structure of this embodiment is shown at the right of
According to the above configuration, the polarized state conversions shown in
As being understood by comparing
As shown in
This embodiment uses the configuration shown in
The structure of this embodiment is shown at the left of
According to the above configuration, the polarized state conversions shown in
As being understood by comparing
As shown in
This embodiment uses the configuration shown in
The structure of this embodiment is shown at the right of
According to the above configuration, the polarized state conversions shown in
As being understood by comparing
As shown in
This embodiment uses the configuration shown in
The structure of this embodiment is shown at the right of
According to the above configuration, polarized state conversions shown in
As being understood by comparing
As shown in
This embodiment uses the configuration shown in
The structure of this embodiment is shown at the left of
This embodiment is described below. In the case of an IPS-mode liquid-crystal display apparatus, the retardation of a liquid-crystal layer normally ranges between 270 and 400 nm in order to obtain sufficiently bright white display. When the absorption axes of first and second polarizers are completely parallel with or vertical to the optical axis of a liquid-crystal layer, in-plane display irregularity is small and a sufficient contrast ratio is obtained. However, it is difficult to avoid a minute axis shift from occurring in production. A case is considered in which the retardation of a liquid-crystal layer is kept in the above range and an axis shift occurs in the optical axis of the liquid-crystal layer.
In the case of this embodiment, 550 nm is obtained by adding retardations of the liquid-crystal layer 15 and optical phase compensation member 17 as shown in
According to our study, advantages of the present invention are obtained when a result of adding retardations of the liquid-crystal layer 15 and optical phase compensation member 17 ranges between 450 and 600 nm. Moreover, in the case of this embodiment, the optical phase compensation member 17 is provided between the first substrate 16 and the liquid-crystal layer 15. As being understood by considering
In the case of e-mode, relative relation to the liquid-crystal-layer optical axis 15S and the polarization-plate absorption axis of the lag axis 17S is reverse to the case of this embodiment.
Moreover, according to our study, advantages same as the case of the present invention are obtained even if the optical phase compensation member 17 has double refraction property same as the case of the negative a-plate.
As shown in
The structure of this embodiment is shown at the left of
This embodiment is described below. When constituting an IPS-mode liquid-crystal display apparatus, it is necessary that a liquid-crystal layer is homogeneous orientation. Therefore, the rubbing technique is used. In this case, it is general that a liquid-crystal molecule slightly tilts from a substrate and a pretilt angle occurs. According to our study, the liquid-crystal-layer pretilt angle impairs the visual-angle characteristic of the IPS-mode liquid-crystal display apparatus. This is described by referring to
According to the above configuration, it is possible to decrease the influence of the liquid-crystal-layer pretilt. This is described by referring to
In this configuration,
Moreover, this embodiment uses a optically biaxial optical phase compensation film having N2 Of 0.5 and retardation of 270 nm as the optical phase compensation member 13. When polarized state changes after incoming light passes through the liquid-crystal layer 15 and optical phase compensation member 17 are realized as shown in
In the case of e-mode, the relative relation to the liquid-crystal-layer optical axis 15S and polarization-plate absorption axis of the lag axis 17S is reverse to the case of this embodiment.
Moreover, according to our study, even if the optical phase compensation member 17 has double refraction property same as the case of the negative a-plate, advantages same as those of the present invention are obtained. In this case, however, it is necessary to substantially equalize the retardation of the liquid-crystal layer 15 with the retardation of the optical phase compensation member 17 and it is necessary that the optical axis 15S of the liquid-crystal layer 15 is orthogonal to the lag axis 17S of the optical phase compensation member 17.
The present invention relates to a liquid-crystal display, particularly to an in-plane-switching-mode (IPS) liquid-crystal display apparatus for controlling transmission and cutoff of light by applying a horizontal electric field to liquid-crystal molecules oriented in the horizontal direction and great improvement of its viewing angle characteristic (black display and low gradation), which can be applied to every IPS-mode liquid-crystal display.
It should be further understood by those skilled in the art that although the foregoing description has been made on embodiments of the invention, the invention is not limited thereto and various changes and modifications may be made without departing from the spirit of the invention and the scope of the appended claims.
Claims
1. A liquid-crystal display apparatus comprising:
- a liquid-crystal layer in which absorption axes of a first substrate having a light-incoming-side polarizer and a second substrate having a second polarizer (smaller angle ranges between 88 and 90°) liquid-crystal molecules are oriented in parallel with the substrates and almost vertical to or in almost parallel with the absorption axis of the first polarizer (smaller angle ranges between 0 and 2°), and the liquid-crystal molecules rotate in a plane parallel with the first substrate by applying an electric field in a direction parallel with the first substrate; and
- a back lighting system in which a matrix-driven electrode group including a pair of electrodes is provided at rear side of liquid-crystal layer by facing each pixel to the side of either of the first substrate or the second substrate whichever is closer to the liquid crystal layer, wherein
- the absorption axis of the first polarizer is almost parallel with the optical axis of the liquid-crystal layer (smaller angle ranges between 0 and 2°) and a support base material of the first polarizer at the liquid-crystal layer side has double refraction property (retardations in plane and thickness direction are 10 nm or more), the support base material of the first polarizer at the liquid-crystal layer side contacts with an optical member or film having double refraction property, and when laminating the support base material of the first polarizer at the liquid-crystal layer side and the optical member or film having the double refraction property, the refraction factor is almost isotropic (retardations in plane and thickness direction are 10 nm or less).
2. A liquid-crystal display apparatus comprising:
- a liquid-crystal layer in which absorption axes of a first substrate having a light-incoming-side polarizer and a second substrate having a second polarizer (smaller angle ranges between 88 and 90°) liquid-crystal molecules are oriented in parallel with the substrates and almost vertical to or in almost parallel with the absorption axis of the first polarizer (smaller angle ranges between 0 and 2°), and the liquid-crystal molecules rotate in a plane parallel with the first substrate by applying an electric field in a direction parallel with the first substrate; and
- a back lighting system in which a matrix-driven electrode group including a pair of electrodes is provided at rear side of liquid-crystal layer by facing each pixel to the side of either of the first substrate or the second substrate whichever is closer to the liquid crystal layer, wherein
- the absorption axis of the first polarizer and the optical axis of the liquid-crystal layer are almost vertical (smaller angle ranges between 88 and 90°), a support base material of the second polarizer at the liquid-crystal layer side has double refraction property (retardations in plane and thickness direction are 10 nm or more), the support base material of the second polarizer at the liquid-crystal layer side contacts with an optical member of film having double refraction property, and when laminating the support base material of the second polarizer at the liquid-crystal layer side and the optical member or film having the double refraction property, refraction factor is almost isotropic (retardations in plane and thickness direction are 10 nm or less).
3. The liquid-crystal display apparatus according to claim 1, wherein
- one or more optical phase compensation members which has double refraction property and compensates a polarized state of transmission polarized light are included between the liquid-crystal layer and the second polarizer.
4. The liquid-crystal display apparatus according to claim 3, wherein
- an optical phase compensation member set between the liquid-crystal layer and the second polarizer has an in-plane lag-axis-directional refraction factor n1, an in-plane phase-advance-directional refraction factor n2, and an in-plane thickness-directional refraction factor n3 and satisfies relations of 0.3(n1−n3)/(n1−n2)<0.7 and 150 nm≦{n3−(n1+n2)/2}dr<400 nm for a thickness dr, and the lag axis of the in-plane optical phase compensation member is almost vertical to the in-plane lag axis of the liquid-crystal layer (smaller angle ranges between 88 and 90°) or almost parallel with the lag axis (smaller angle ranges between 0 and 2°.
5. The liquid-crystal display apparatus according to claim 3, wherein
- a first optical phase compensation member is provided at the liquid-crystal layer side and a second optical phase compensation member is provided at the second polarizer side as optical compensation members set between the liquid-crystal layer and the second polarizer, the first optical phase compensation member has an in-plane lag-axis-directional refraction factor n1, an in-plane phase-advance-axis-directional refraction factor n2, and an in-plane thickness-directional refraction factor n3 and satisfies relations of (n1−n3)/(n−n2)<0.5 and 20 nm≦{n3−(n1+n2)/2}dr<180 nm for a thickness dr, the second optical phase compensation member has an in-plane phase-advance-axis-directional refraction factor n1, an in-plane phase-advance-axis-directional refraction factor n2, and an in-plane thickness-directional refraction factor n3 and satisfies relations of (n−n3)/(n1−n2)>0.5 and 20 nm≦{n3−(n1+n2)/r}dr<180 nm for a thickness dr and lag axes of the in-plane first and second optical phase compensation members are almost parallel with the in-plane lag axis of the liquid-crystal layer (smaller angle ranges between 0 and 2°).
6. The liquid-crystal display apparatus according to claim 3, wherein
- a first optical phase compensation member is provided at the liquid-crystal layer side and a second optical phase compensation member is provided at the second polarizer side as optical phase compensation members set between the liquid-crystal layer and the second polarizer, the first optical phase compensation member has an in-plane lag-axis-directional refraction factor n1, an in-plane phase-advance-axis-directional refraction factor n2, and an in-plane thickness-directional refraction factor n3 and satisfies relations of (n1−n3)/(n1−n2)>0.5 and 20 nm≦{n3−(n1+n2)/2}dr≦180 nm for a thickness dr, the second optical phase compensation member has an in-plane lag-axis-directional refraction factor n1, an in-plane phase-advance-axis-directional refraction factor n2, and an in-plane thickness-directional refraction factor n3 and satisfies relations of (n1−n3)/(n1−n2)<0.5 and 20 nm>{n3−(n1+n2)/2}dr≦180 nm for a thickness dr, and the in-plane lag axes of the first and second optical phase compensation members are almost vertical to the in-plane lag axis of the liquid-crystal layer (angel of smaller one ranges between 88 and 90°).
7. The liquid-crystal display apparatus according to claim 3, wherein
- a first optical phase compensation member is provided at the liquid-crystal layer side and a second optical phase compensation member is provided at the second polarizer side as optical phase compensation members set between the liquid-crystal layer and the second polarizer, the first optical phase compensation member has an in-plane lag-axis-directional refraction factor n1, an in-plane phase-advance-axis-directional refraction factor n2, and an in-plane thickness-directional refraction factor n3 and satisfies relations of 0.65<(n1−n3)/(n1−n2)<0.85 and 200 nm{n3−(n1+n2)/2}dr≦350 nm for a thickness dr, the second optical phase compensation member has an in-plane lag-axis-directional refraction factor n1, an in-plane phase-advance-axis-directional refraction factor n2, and an in-plane thickness-directional refraction factor n3, satisfies relations of 0.15<(n1−n3)/(n1−n2)<0.35 and 200 nm≦n3−(n1+n2)/2}dr≦350 nm for a thickness dr, and in-plane lag axes of the first and second optical phase compensation members are almost parallel with the in-plane lag axis of the liquid-crystal layer (smaller angle ranges between 0 and 2°).
8. The liquid-crystal display apparatus according to claim 3, wherein a first optical phase compensation member is provided to the liquid-crystal layer side and a second optical phase compensation member is provided to the second polarizer side as optical phase compensation members set between the liquid-crystal layer and the second polarizer, the first optical phase compensation member has an in-plane lag-axis-directional refraction factor n1, an in-plane phase-advance-axis-directional refraction factor n2, and an in-plane thickness-directional refraction factor n3 and satisfies relations of 0.15<(n1−n3)/(n1−n2)<0.35 and 200 nm≦{n3−(n1+n2)/2}dr≦350 nm for a thickness dr, the second optical phase compensation member has an in-plane lag-axis-directional refraction factor n1, an in-plane phase-advance-axis-directional refraction factor n2, and an in-plane thickness-directional refraction factor n3 and satisfies relations of 0.65<(n1−n3)/(n1−n2)<0.85 and 200 nm≦{n3−(n1+n2)/2}dr≦350 nm for a thickness dr, and the in-plane lag axes of the first and second optical phase compensation members are almost vertical to the in-plane lag axis of the liquid-crystal layer (smaller angle ranges between 88 and 90°).
9. The liquid-crystal display apparatus according to claim 2, wherein
- one or more optical phase compensation members which have double refraction property and compensate a polarized state of transmitted polarized light are included between the liquid-crystal layer and the first polarizer.
10. The liquid-crystal display apparatus according to claim 9, wherein
- an optical phase compensation member set between the liquid-crystal layer and the polarizer has an in-plane lag-axis-directional refraction factor n1, an in-plane phase-advance-axis-directional refraction factor n2, and a thickness-directional refraction factor n3 and satisfies relations of 0.3<n1−n3)/(n1−n2)<0.7 and 150 nm≦{n3−(n1+n2)/2}dr≦400 nm for a thickness dr, and the in-plane lag axis of the optical phase compensation member is almost vertical to the in-plane lag axis of the liquid-crystal layer (smaller angle ranges between 88 and 90°) or almost parallel with the lag axis (smaller angle ranges between 0 and 2°).
11. The liquid-crystal display apparatus according to claim 9, wherein
- a first optical phase compensation member is provided to the first polarizer and a second optical phase compensation member is provided to the liquid-crystal layer side as optical phase compensation members between the liquid-crystal layer and the first polarizer, the first optical phase compensation member has an in-plane lag-phase-directional refraction factor n1, an in-plane phase-advance-axis-directional refraction factor n2, and an in-plane thickness-directional refraction factor n3 and satisfies relations of (n1−n3)/(n1−n2)>0.5 and 20 nm≦{n3−(n1+n2)/2}dr<180 nm for a thickness dr, the second optical phase compensation member has an in-plane lag-axis-directional refraction factor n1, an in-plane phase-advance-axis-directional refraction factor n2, and a thickness-directional refraction factor n3 and satisfies relations of (n1−n3)/(n1−n2)<0.5 and 20 nm≦{n3−(n1+n2)/2}dr≦180 nm for a thickness dr, and in-plane lag axes of the first and second optical phase compensation members are almost parallel with the in-plane lag axis of the liquid-crystal layer (smaller angle ranges between 0 and 2°).
12. The liquid-crystal display apparatus according to claim 9, wherein a first optical phase compensation member is provided to the first polarizer side, a second optical phase compensation member is provided to the liquid-crystal layer side as optical phase compensation members set between the liquid-crystal layer and the first polarizer, the first optical phase compensation member has an in-plane lag-axis-directional refraction factor n1, an in-plane phase-advance-axis-directional refraction factor n2, and a thickness-directional refraction factor n3 and satisfies relations of (n1−n3)/(n1−n2)<0.5 and 20 nm{n3−(n1+n2)/2}dr≦180 nm for a thickness dr, the second optical phase compensation member has an in-plane lag-axis-directional refraction factor n1, an in-plane phase-advance-axis-directional refraction factor n2, and thickness-directional refraction factor n3 and satisfies relations of (n1−n3)/(n1−n2)>0.5 and 20 nm≦{n3−(n1+n2)/2}dr≦180 nm for a thickness dr, and in-plane lag-axes of the first and second optical phase compensation members are almost vertical to the in-plane lag axis of the liquid-crystal layer (smaller angle ranges between 0 and 2°).
13. The liquid-crystal display apparatus according to claim 9, wherein
- a first optical phase compensation member is provided to the first polarizer and a second optical phase compensation member is provided to the liquid-crystal layer as optical phase compensation members set between the liquid-crystal layer and the first polarizer, the first optical phase compensation member has an in-plane lag-axis-directional refraction factor n1, an in-plane phase-advance-axis-directional refraction factor n2, and a thickness-directional refraction factor n3 and satisfies relations of 0.15<(n1−n3)/(n1−n2)<0.35 and 200 nm>{n3−(n1+n2)/2}dr≦350 nm for a thickness dr, the second optical phase compensation member has an in-plane lag-axis-directional refraction factor n1, an in-plane phase-advance-axis-directional refraction factor n2, and thickness directional refraction factor n3 and satisfies relations of 0.65<(n1−n3)/(n1−n2)<0.85 and 200 nm≦{n3−(n1+n2)/2}dr≦350 nm for a thickness dr, and in-plane lag axes of the first and second optical phase compensation members are almost parallel with the in-plane phase advance axis of the liquid-crystal layer (smaller angle ranges between 0 and 2°).
14. The liquid-crystal display apparatus according to claim 9, wherein
- a first optical phase compensation member is provided to the first polarizer and a second optical phase compensation member is provided to the liquid-crystal layer as optical phase compensation members set between the liquid-crystal layer and the first polarizer, the first optical phase compensation member has an in-plane lag-axis-directional refraction factor n1, an in-plane phase-advance-axis-directional refraction factor n2, and a thickness-directional refraction factor n3 and satisfies relations of 0.65<(n1−n3)/(n1−n2)<0.85 and 200 nm≦{n3−(n1+n2)/2}dr≦350 nm for a thickness dr, the second optical phase compensation member has an in-plane lag-axis-directional refraction factor n1, an in-plane phase-advance-axis-directional refraction factor n2, and thickness directional refraction factor n3 and satisfies relations of 0.15<(n1−n3)/(n1−n2)<0.35 and 200 nm≦{n3−(n1+n2)/2}dr<350 nm for a thickness dr, and in-plane lag axes of the first and second optical phase compensation members are almost vertical to the in-plane lag axis of the liquid-crystal layer (smaller angle ranges between 88 and 90°).
15. A liquid-crystal display apparatus comprising:
- a liquid-crystal layer in which absorption axes of a first substrate having a light-incoming-side polarizer and a second substrate having a second polarizer (smaller angle ranges between 88 and 90°) liquid-crystal molecules are oriented in parallel with the substrates and almost vertical to or in almost parallel with the absorption axis of the first polarizer (smaller angle ranges between 0 and 2°), and the liquid-crystal molecules rotate in a plane parallel with the first substrate by applying an electric field in a direction parallel with the first substrate; and
- a back lighting system in which a matrix-driven electrode group including a pair of electrodes is provided by facing each pixel to the side of either of the first substrate or the second substrate whichever is closer to the liquid crystal layer, wherein
- the first and second polarizers are respectively a polarizer having a support base material at both sides of a polarization layer, the support base material has double refraction property (retardations in plane and thickness direction are 10 nm or more), a support base material provided to the liquid-crystal layer sides of the first and second polarizers respectively show almost-equal double refraction property (retardation difference in plane or thickness direction is 20 nm or less), and an optical phase compensation member having double refraction property (retardation in plane or thickness direction is 20 nm or more) is provided between the first substrate and the liquid-crystal layer.
16. A liquid-crystal display apparatus comprising:
- a liquid-crystal layer in which absorption axes of a first substrate having a light-incoming-side polarizer and a second substrate having a second polarizer (smaller angle ranges between 88 and 90°) liquid-crystal molecules are oriented in parallel with the substrates and almost vertical to or in almost parallel with the absorption axis of the first polarizer (smaller angle ranges between 0 and 2°), and the liquid-crystal molecules rotate in a plane parallel with the first substrate by applying an electric field in a direction parallel with the first substrate; and
- a back lighting system in which a matrix-driven electrode group including a pair of electrodes is provided by facing each pixel to the side of either of the first substrate or the second substrate whichever is closer to the liquid crystal layer, wherein
- the first and second polarizers are respectively a polarizer having a support base material at both sides of a polarization layer, the support base material has double refraction property (retardations in plane and thickness direction are 10 nm or more), a support base material provided to the liquid-crystal layer sides of the first and second polarizers respectively show almost-equal double refraction property (retardation difference in plane or thickness direction is 20 nm or less), and an optical phase compensation member having double refraction property (retardation in plane or thickness direction is 20 nm or more) is provided between the liquid-crystal layer and the second substrate.
17. The liquid-crystal display apparatus according to claim 15, wherein
- support base materials of the first and second polarizers set to the liquid-crystal layer side satisfy a relation of n1≦n3>n2 for an in-plane lag-axis-directional refraction factor n1, an in-plane phase-advance-axis-directional refraction factor n2, and a thickness-directional refraction factor n3, an optical phase compensation member set between the first substrate and the liquid-crystal layer satisfies a relation of n1>n2≦n3 and the support base materials of the first and second polarizers set to the liquid-crystal layer side and the in-plate lag axis of an optical phase compensation member set between the first substrate and the liquid-crystal layer are almost parallel with the absorption axis of the first polarizer (smaller angle ranges between 0 and 2°) or almost vertical to the absorption axis (smaller angle ranges between 88 and 90°).
18. The liquid-crystal display apparatus according to claim 15, wherein
- support base materials of the first and second polarizers set to the liquid-crystal layer side satisfy a relation of n1≦n3>n2 for an in-plane lag-axis-directional refraction factor n1, an in-plane phase-advance-axis-directional refraction factor n2, and a thickness-directional refraction factor n3, an optical phase compensation member set between the first substrate and the liquid-crystal layer satisfies a relation of n1>n2≦n3 and support base materials of the first and second polarizers set to the liquid-crystal layer side and the in-plate lag axis of an optical phase compensation member set between the first substrate and the liquid-crystal layer are almost parallel with the absorption axis of the first polarizer (smaller angle ranges between 0 and 2°) or almost vertical to the absorption axis (smaller angle ranges between 88 and 90°).
19. The liquid-crystal display apparatus according to claim 16, wherein
- support base materials of the first and second polarizers set to the liquid-crystal layer side satisfy a relation of n1≦n3>n2 for an in-plane lag-axis-directional refraction factor n1, an in-plane phase-advance-axis-directional refraction factor n2, and a thickness-directional refraction factor n3, an optical phase compensation member set between the liquid-crystal layer and the second substrate satisfies a relation of n1>n2≦n3 and support base materials of the first and second polarizers set to the liquid-crystal layer side and the in-plate lag axis of an optical phase compensation member set between the liquid-crystal layer and the second substrate are almost parallel with the absorption axis of the first polarizer (smaller angle ranges between 0 and 2°) or almost vertical to the absorption axis (smaller angle ranges between 88 and 90°).
20. The liquid-crystal display apparatus according to claim 16, wherein support base materials of the first and second polarizers set to the liquid-crystal layer side satisfy a relation of n1≦n3>n2 for an in-plane lag-axis-directional refraction factor n1, an in-plane phase-advance-axis-directional refraction factor n2, and a thickness-directional refraction factor n3, an optical phase compensation member set between the liquid-crystal layer and the second substrate satisfies a relation of n1≦n3>n2 and support base materials of the first and second polarizers set to the liquid-crystal layer side and the in-plate lag axis of an optical phase compensation member set between the liquid-crystal layer and the second substrate are almost parallel with the absorption axis of the first polarizer (smaller angle ranges between 0 and 2°) or almost vertical to the absorption axis (smaller angle ranges between 88 and 90°).
21. A liquid-crystal display apparatus comprising:
- a liquid-crystal layer in which absorption axes of a first substrate having a light-incoming-side polarizer and a second substrate having a second polarizer (smaller angle ranges between 88 and 90°) liquid-crystal molecules are oriented in parallel with the substrates and almost vertical to or in almost parallel with the absorption axis of the first polarizer (smaller angle ranges between 0 and 2°), and the liquid-crystal molecules rotate in a plane parallel with the first substrate by applying an electric field in a direction parallel with the first substrate; and
- a back lighting system in which a matrix-driven electrode group including a pair of electrodes is provided by facing each pixel to the side of either of the first substrate or the second substrate whichever is closer to the liquid crystal layer, wherein
- an optical phase compensation member having double refraction property is provided between the first and second substrates in addition to the liquid-crystal layer, the optical axis of the liquid-crystal layer is almost parallel with the lag axis of the optical phase compensation member, the optical phase compensation member satisfies n1>n2≦n3 for an in-plane lag-axis-directional refraction factor n1, an in-plane phase-advance-axis-directional refraction factor n2, and a thickness-directional refraction factor n3, and the sum of in-plane retardations of the liquid-crystal layer and the optical phase compensation member ranges between 450 and 600 nm (both included).
22. The liquid-crystal display apparatus according to claim 21, wherein
- tilt angles of the optical axis of the liquid-crystal layer and the lag axis of the optical phase compensation member to the first substrate are almost equal to each other (angle difference is kept within ±1°).
Type: Application
Filed: Feb 6, 2006
Publication Date: Aug 10, 2006
Patent Grant number: 7719647
Inventors: Daisuke Kajita (Hitachi), Ikuo Hiyama (Hitachinaka), Masahiro Ishii (Chiba)
Application Number: 11/347,250
International Classification: G02F 1/1335 (20060101);
